Posted
by
kdawsonon Tuesday January 05, 2010 @06:00PM
from the from-little-seeds dept.

FiReaNGeL writes "Astronomers, using NASA's Hubble Space Telescope, have uncovered a primordial population of compact and ultra-blue galaxies that have never been seen before. They are from 13 billion years ago, just 600 to 800 million years after the Big Bang. These newly found objects are crucial to understanding the evolutionary link between the birth of the first stars, the formation of the first galaxies, and the sequence of evolutionary events that resulted in the assembly of our Milky Way and the other 'mature' elliptical and majestic spiral galaxies in today's universe."

How soon they form depend on your cosmological simulation. Something had to be forming to reionize the universe, but it did not have to be galaxies of a sufficient size that you would notice them. But, the further the existence of quasars was pushed back, the more you needed somewhat organized bodied in which they could form even earlier so there were indications that some massive galaxies form early.

They've already found the closest thing to the big bang that's visible: the hot dense opaque plasma that's visible as the cosmic microwave background radiation, the characteristics of which coincide perfectly with the big bag theory.

It's like this: I don't understand Big Bang Theory, therefore I don't like it, therefore it's nonsense, therefore your "evidence" is really just your prejudice, therefore we're obviously going to find galaxies that are ten billion years older than these ones, and therefore my theory of the Giant Cosmic Bunny Orgy Theory, which is obvious if you even think about it rationally, will be proven correct once and for all and I'll be elected the President of Physics. [xkcd.com]

Not smart enough? Parental pressure to follow your father into plumbing? A death in the family during a critical part of your schooling? Lived too far from suitable tertiary institutions? Can I have a hint?:P

It may be. That is about a dynamical timescale for a galaxy merger. Star formation takes much less time than 600 million years. You would not be forming a lot of earth-like planets at that time because there was very little in the way of dust early on. Most solid phase material may have been ice rather than dust owing to the early relatively high abundance of oxygen produced in pair-instability supernovae.

Here is a classic paper on galaxy formation: http://articles.adsabs.harvard.edu/full/1977MNRAS.179..541R [harvard.edu] you can get rough timescales from there. More modern treatments include early clustering of dark matter to speed the process along. Dark matter obviates the need to worry about cooling times to some extent though consideration of lithium hydride cooling may be important before the first prompt supernovae provide some metals (most likely pair-instability SNe). You can find out more in my paper linked above.

Actually, the warm background can interfere with gas clouds cooling enough to collapse to become stars since the gas needs to cool radiatively. So, the warmth of the universe is a hindrance to some extent.

My understanding of cosmology is at best limited, but shouldn't these galaxies appear red-shifted to the extreme? They are furthest and hence should be moving the away from us at an extremely fast pace. Is the name Ultra-blue restricted to element analysis based on spectrum? I'm just confused about the blue light.

My understanding of cosmology is at best limited, but shouldn't these galaxies appear red-shifted to the extreme? They are furthest and hence should be moving the away from us at an extremely fast pace. Is the name Ultra-blue restricted to element analysis based on spectrum? I'm just confused about the blue light.

Looking at this bit:

They are so blue that they must be extremely deficient in heavy elements, thus representing a population that has nearly primordial characteristics."

I assume this means that light, hydrogen-heavy objects will get hotter for a given amount of heat energy because of their lower density. Maybe these galaxies are red shifted, but they are relatively blue in relation to their red shift.

Yes but considering most of the observable universe appears to be hydrogen that's a SHIT LOAD of mass to burn through.

I'll add to this that if the light is 13 billion years old, the galaxies might have burned through everything by now but we wouldn't know because the light carrying the information to witness the change hasn't physically reached us yet.

There is a lot of recycling that goes on so most stars now are made of material that was in a previous generation of stars. But, there are stars in our galaxy from those early times. They are low enough mass (less than 0.7 times the mass of the Sun) so that they have lifetimes longer than the age of the universe. Certain globular clusters in the Milky Way appear to be from about that time.

Offtopic, but WTHell: Watch Cosmos again and be on the lookout for "billions and billions", and it's not there, anywhere at all. This was uttered by Johnny Carson, in a Tonight Show bit where he parodied Carl. But the phrase turned out to be too good to not be true, so it became a classic case of "print the legend".

This is just a guess, but I'm thinking you can look for spectral lines characteristic of certain elements and simple compounds, and see how far down the spectrum they're shifted, to determine the overall degree of redshift. Once you have that information, you have a pretty good idea how far away the galaxy is. Any astronomers want to jump in and tell me if this is right, wrong, or "not even wrong?"

I'm not an astronomer, but I did take a course once. You're right and wrong. By itself, the red shift will only tell you how fast it is moving relative to you. It won't directly tell you how far. Astronomers have pieced together a bunch of distance determining methods into what they call the Cosmic Distance Ladder [wikipedia.org]. In general, the larger the red shift, the farther away the object, but not always. Certain regions of the sky have smaller or larger red shifts than they are "supposed" to have. These diffe

Elements emit light at characteristic colors - frequencies of light. Eg, copper emits a bluish green color. By looking at the spectrum of the object, you can tell what the object is made of. If an object is moving, the spectrum will be shifted relative to normal due to the doppler effect. If it is shifted to higher frequencies the object is approaching you. If the spectrum is red shifted, it is moving away. The greater the shift, the greater the velocity.

Certain stars are close enough to Earth that we can triangulate their distance, using the orbit of the earth as the base of the triange. There is a certain class of star called a cepheid variable, some of which are in triangulateable range. Cepheids give off regular bursts of light, and due to the process by which they do that, the amount of light they give off is proportional to the frequency of the bursts. By using the inverse square law you can tell how far away a cepheid is by its brightness.

Thus, you can tell how far away a galaxy is by looking at its cepheid stars. So, by careful observation, you can detect the composition, speed, direction, distance, and age of a star. By looking at many stars, you can detect patterns like: the farther away a star is, the faster it is moving away from us.

To clarify so the GP doesn't think copper emits some blurred haze of green, elements emit very specific wavelenths of light that can be easily differentiated when the light is separated via a prism.

You'll see bands of light of various strenghts, and very conspicuous black lines at frequencies where it does not emit any light. Because the light was emmitted at the exact same moment (by definition), the redshift is exactly the same for all frequencies. The pattern never changes even though the the light all

You have a telescope that receives light from a distant object. At first:

-you don't know what it is made of

-you don't know how far away it is

-and you don't know how fast its relative motion is

How can you use red shift to predict relative motion? A shift implies a motion, and you don't know where it is moving from.

How can you make any prediction about composition if you can't be sure of the shift?

How can you make and prediction about distance if you are making up numbers about the previous two?

I've got to read a book or two on cosmology sometime. I suspect there is a lot of 'splaining left out.

And I would expect the oldest galaxies to have the least amount of hydrogen left, having had stars burning it the longest.

It goes like this:
You use epctral analysis to determine what its made of by looking for known patterns in the spectrum of the light

You measure the redshift, to estimate the distance you either guess the absolute magnitude (which can often be done with gallaxies to at least give an upper limit) or you use hubbles law and assuming you have a good value of hubbles parameter you can convert red shift to distance. This is a bit circular and relies on you allready having found the distance of lots of object

Also worth mentioning that the Big Bang wasn't an event where a bunch of stuff existed as a dot within a big infinite space. Prior to the Big Bang there was no space and no time. Space itself inflated as a shared property of all energy. Space continues to inflate in the same manner. And given that the expansion is accelerating it looks as though space begets space.

The light we're seeing comes from a long long time ago, from when the galaxies were actually getting closer. Either that or it's because it's from such a long time ago that stars had only managed to produce the smaller elements and so were bluer because of the lack of oxygen. At least, that's the colour I go when I'm lacking oxygen, I assume galaxies are the same.

Actually it's because the galaxy is almost entirely hydrogen, which emits blue light.

What they picked up was infra-red light. By shining that through a prism, you get the elements the galaxy is composed of. From the elements you can get the original color (all elements radiate a very specific set of frequencies that act like a fingerprint). Compare the original color to the observed color, which has shifted so far it has gone from up near violet down into the infra-red, and you get distance and therefore

would they actually be using a physical prism anyway? Seems like a great way to lose a bunch of those precious photons, I'd think it'd be better done mathmatically with rather large computers with lots of bits... if ya think, spectrum analysis on audio has been well within the reach of computers for quite some time, fundamentally I can't imagine it being too different. In which case, infra red, microwave, radiowave, you just need a larger window to analyse to fit enough of the wavelength in.

I believe the only reason they can see these galaxies is because they were blue to begin with.

They are using Hubble's infra-red telescope to see them, so that should tell you how far they have shifted. Obviously the pretty picture has been adjusted back to the original color. If you'll notice, the older galaxies (from 600 mil years post Big Bang) are a darker blue than the younger (700 mil years post BB).

They are extremely red-shifted (in fact astronomers typically talk about such distances/timescales in terms of degree of red-shift). It's not like if you were to peer at these galaxies in a telescope they'd look blue. In fact you probably wouldn't see anything at all; Hubble is almost certainly (huh? rtfa?) using it's near-infrared cameras for this.

The article didn't explain the "rest wavelength" that was noted above in a comment. That's what I was looking for. The light has been "shifted back" to how it would appear if there was no relative movement between observer and the target galaxy.

I *think* TFA is implying that they can determine the intrinsic color, even when highly red-shifted, and that this intrinsic color is extremely blue due to the lack of any elements other than hydrogen and helium. This would be expected, because no elements heavier than helium had yet been synthesized.

Different elements have a very distinct pattern of frequencies of light they emit when they are radiating. Since we can cause these elements to radiate on Earth to see what the base frequencies are, all we have to do is compare the pattern to the known patterns of the elements to figure out the primary elements in the galaxy. From there we can compare the base frequencies to the red-shifted frequencies and get distance/time. Hydrogen is mostly various blue wav

In theory, at the very edge of universe, is it possible that the primordial light has yet made itself visible? if someone could.. in theory.. travel there, would they be able to see the very creation itself?

Are you asking about the edge as it was when the light we might detect now was emitted billions of years ago or the edge as it is now? I find it kind of difficult to speculate about the later since we're always billions of years behind of any sight we may get from it...

According to TFA, hydrogen re-ionization when most of the universe was still opaque, gassy hydrogen and was not burning in the form of stars, blocks almost all of the light from 400 million to 900 million years after the BB. The only reason these galaxies were visible is because they believe they had extremely efficient hydrogen ionization, which is also why they were so blue. Before 400 million years post BB you have stars and galaxies only just forming, so I don't think there would be much in the way of

I know a lot of people use the term "evolutionary" as a synonym for "gradual" or "slow" but when I think of evolution, I think of the specific process of mutations and reproduction by which a population changes over time. Unless there's something new about galaxies I've never heard of, I don't understand why the term "evolutionary" is the best word to describe the development of the early universe. (Or anything at astronomical scales that I can think of.)

Darwinian selection is the process by which animal species change over time. That is one example of evolution, a specific example which happens to rely on hereditary characteristics, reproduction, and so forth.

But 'evolution' is a word that simply means change over time. Evolution was used as a term long before Darwin; indeed, it was known that animals evolved before there was any good explanation for how they evolved.
The term 'evolution' isn't limited to living creatures any more than the term 'driv

Ok, I admit I don't know a lot about this subject, but if they are seeing this far into the "past", they have to be looking in one direction right? I assume that the Big Bang started at one point. So therefore, there must be one spot in the sky that they are looking at, and thus the "spot" that the universe came into existence.

Is this spot in the sky widely known? Where is it? And assuming the explosion would be spherical, would we ever be able to see galaxies that shot off in the other directions?

if they are seeing this far into the "past", they have to be looking in one direction right? I assume that the Big Bang started at one point.

The sibling post gives a perfectly good analogy to explain this, but you probably already knew it. Another way of putting it that I sometimes find helpful: the Big Bang didn't happen at such-and-such a location, which can be plotted as X, Y, Z coordinates. The Big Bang happened everywhere. It's just that Everywhere was really really really tiny back then.

Another way to look at it, is that at the instant before the big bang there was no universe, or you could say the universe was infinitely small. After the BB the universe was expanding, but there was still no space outside the universe. Everything we consider "space" is all packed inside the universe, and the universe was a lot smaller then than it is.

The classic analogy is the balloon analogy. Imagine three dimensional space is the two dimensional surface of a balloon with tiny points all over it representing matter. As the balloon expands, all points on the surface move away from each other, and the balloon has gotten larger. However, the center of the balloon is not on the 2d surface, the center of the balloon is in the 3rd dimension. Therefore, relative to the surface there is no center.

Now, bump everything up one dimension and you have our universe. The "surface" is three dimensional space, and it is expanding along the fourth dimension. We have no way of seeing the fourth dimension, just like a 2d creature on the surface of the balloon could do nothing but look forward, backward, left and right we can only do that plus up and down. We would need to add another dimension to our repertoir to view the fourth dimension, but we can't conceptualise beyond the abstract about what that might be. However, we can definitely see that everything in the third dimension is moving away from everything else. Therefore space is expanding, and no matter which way we look everything is moving away. In fact, no matter what vantage point you take in the universe it will always look the same, because the "surface" of the universe is what is expanding.

It's a bit mind numbing to think about, but there is no direction you can look at and figure out "where" the big bang was. There is no "where" in the third dimension, the where is in a dimension that we are not equipped to experience. All we can do is measure its effects in our own dimension.

I like Carl Sagan's explanation of the fourth dimension best, but wikipedia [wikipedia.org] does a good job, if a bit on the technical side.

I have a followup question to this: Is the universe now, or did it ever, expand at or faster than the speed of light, as space itself expanded? The whole notion of looking 'back in time' to see a galaxy that close to the big bang has me a little bit puzzled. What I mean is, my understanding of this whole idea of 'looking back in time' with a telescope is that light travels at the speed of light, and if we know a galaxy is X billion light-years away from Earth, then we say that the images we see *now* origin

I have wondered this for SO long, and it would be really interesting to hear a qualified answer. That being said I will take a crack at how I think this may be possible. I think I, and most people, are thinking about the universe wrong. The universe is not some object, everything inside it is, and everything inside the universe abides by the laws of physics. So the universe can expand at what ever rate it wants. I know this brings up the problem of things much be traveling away from each other faster than

This probably does not help much but the cosmological redshift is not from velocity but rather from space stretching along the path of the photon, which stretches the photon, increasing its wavelength.

I like Carl Sagan's explanation of the fourth dimension best, but wikipedia [wikipedia.org] does a good job, if a bit on the technical side.

But the wikipedia article on the fifth dimension [wikipedia.org] can help clarify the issue much more. Your balloon analogy doesn't hold up, when it goes up, up and away. It's almost as if you are claiming that in three dimensions, we have a sweet blindness of the fourth. When in fact, using the fifth dimension, you can go where you want to go.

Once you observe using the fifth dimension, everything's changed. We're observing these distance galaxies in the constellation Aquarius, while trying to let the sun shine in. Bu

The BB is still happening, the "expansion" of the observable universe (small 'u') is just another way of saying space is still exploding into existance, in otherwords the universe IS the big bang. The cosmic microwave background (CMB) is a shell of expanding "light" that came from very early in the long bang. The CMB encloses our universe.

It's claimed that the CMB shell is a universal frame of reference until recently it had been assumed no such universal frame of reference existed, however it's existanc

- We know that the universe started expanding from a single point.- We also know that there are galaxies which are billions of light-years away from us.- This implies that the universe must haveexpanded faster than the speed of light after the big-bang explosion.

I cant wrap my head around that. How is faster than light expansion possible?

Those galaxies have had a lot of time to develop life. Maybe prioritize that direction for SETI...

I can't make sense of this.

If we can observe these galaxies as they appeared 13 Billion years ago, then any SETI observation would be an observation of how they looked 13 Billion years ago. And so the "lot of time to develop life" is irrelevant (unless I let my SETI@Home program run for 13 Billion years...)

When they manage to spot a body in space that, by the very best methods they can use to attain the age of very distant objects, which seems to be, oh... say, about 22 billion years old, they're going to scratch their heads and mutter, "well... that's odd".

As we observe objects at greater and greater distances, they have to keep revising their age-estimate of the universe. In the end, I think that they will eventually conclude the universe is infinitely vast, and infinitely old. This of course implies th

As we observe objects at greater and greater distances, they have to keep revising their age-estimate of the universe.

And here we have spotted the farthest-away objects ever, and it required no revision of the age of the universe. There has been some adjustment towards 'older', but most of the time these days when the age of the universe is adjusted, it's towards more precision, not increasing age.

x can be UNEQUAL to y. So we can have infinite mass, distributed in an infinite volume, in a universe with nei

The point was and is, just as when the Catholic Church was considered the guardian of all knowledge, (at least in Europe,) and an observation was made which pointed out that one of their stances was incorrect, (by being in direct contravention to what was observed,) they resisted, tormented those who disagreed, but ultimately had to revise their position when it became obvious they were wrong; so it is today.

And my counter point is that if the Church was Science, Copernicus and Galileo would have been hera

I believe the universe had no beginning, will have no end, and either way it doesn't matter because the entire span of my life is so short I'll never know either way.

And you know what? If all you had said is that you have this belief, then I wouldn't have taken issue with your post at all. I have beliefs too. You can have a good, rational discussion about beliefs as long as you acknowledge them as such. Beliefs aren't evidence, though, which is where philosophy diverges from science even though the latt

You ask a lot of important questions, but most of them come from a misunderstanding of the situation - what you might call the prejudice of being *inside* the system. But keep pursuing those questions! And be careful about your attitude towards the word "theory." By placing the word in bold, you're emphasizing its informal usage, which stresses uncertainty. But in science the word has a formal meaning. In the parlance of science the most *certain* models that exist are theories. For what you're trying to ex

In fact, they are spread out somewhat in appearance because there is no "vanishing point" as you might have in a drawing with a road or rail tracks. The smaller universe of that time has to be spread over the same amount of sky so there is some magnification to make this happen. Try putting different redshifts in here http://www.astro.ucla.edu/~wright/CosmoCalc.html [ucla.edu] and look at how the scale changes (kpc/" is kiloparsecs per arcsecond). You can plot it on some paper and see how it changes.

It has to do with the expanding universe, period. Take a balloon and draw a bunch of regularly spaced dots on it with a marker. Now inflate the balloon. The dots all get farther away from each other. Moreover, there is no "center" to the expansion that lies on the surface of the balloon -- no one point can be said to be the center from which all other points move away. In this analogy, the speed of light would be the maximum speed at which the dots could move about on the surface of the balloon -- this is t

If that were true, then there would be a central point that everything else was expanding away from. It would also imply an edge to the universe. The balloon analogy reduces space to two dimensions, but in reality there are three, so you need to imagine a "hyperballoon." It's still only an analogy, but it helps understand the geometry of what we think is happening.